Demons

by Matt McIrvin

A big man with a cardboard sign meets me in the arrival vestibule, before I even have a chance to buy some clothes and shuck my airline suit. They’d told me not to ship any baggage, so no trouble there, but visitors aren’t normally allowed in here.

Something’s breaking on the screen by the shuttle stop, something about 200 dead in Dallas. The sound is pretty low and I miss most of the scrolling text. The big uniformed guy sees me squinting at the screen, puts a heavy arm around my shoulder and shakes his head. “Plenty of time for that later,” he says, and motions me out a side door marked AUTHORIZED PERSONNEL ONLY.

There’s a breeze out on the tarmac, and it chills me through the suit. The waistband is starting to rip and of course I’ve got nothing on under there. I feel ridiculous. There’s a Dreamland Air logo a foot high on my chest: clouds and pink cherubim. Fortunately it’s a short walk to the car, a drab unmarked affair parked right at the bottom of the metal stairs between a fuel truck and a forklift.

He sets the car on automatic, but it’s not taking the Expressway; it’s all back roads, in from the tip of Long Island. There’s some equipment I can’t identify in the car, wired to the windows. He starts to brief me, but he doesn’t know much. “Your experience and skill in the breeding of nanomechanisms are needed at the site. I have been told that this project could win the war.” I’m not going to argue; no more holy plague would be good enough for me.

“For the past seven years, we have had a small team here doing fundamental research on the measurement problem in quantum mechanics,” says Dr. Patel. I sit in the only occupied chair in the darkened colloquium room, wearing a ragged bathrobe belonging to one of her grad students. She’s showing me an animated 3D micrograph of some sort of nanocircuit attached to a living cell. The cell is covered with branching tendrils and has a sort of long neck: a neuron, I suppose. The circuit is all over the thing, like a wire basket, and there’s a little box with a couple of leads stretching out of the picture.

“That looks biological,” I say.

She nods. “We have confirmed Wigner’s hypothesis of the central role of the brain in wave-function collapse.”

I’m irritated. They hauled my naked butt out on the tarmac in March at Giuliani for this? “Wigner was confused. There’s nothing special about the brain except that it’s a thermodynamically irreversible system. If an observable gets coupled to the brain state, there’s gotta be decoherence. You can explain everything about so-called collapse by just assuming that.”

“No, you can’t,” says Patel, giving me a lopsided smile.

“What can’t you explain?”

“The collapse is not irreversible. We have reversed it.”

My jaw drops. “You have not.”

They have. Her students Tianbao and Nora give me a tour of the experimental lab that afternoon. Their apparatus, on a heavy optical table in the twilit room, is mostly an ordinary optical interferometer, though there’s more… plumbing than I’d expect in such a lab. Photons from a weak light source hit a half-silvered mirror, and continue on either of two paths through a series of mirrors and lenses, to be recombined at a detector, a device like the business end of a digital camera. The arriving photons, summed up over time, should show an interference pattern of light and dark fringes, provided that no steps are taken to identify which path an individual photon takes.

But the beam in each leg of the interferometer also goes through a cylindrical cell containing an optically active crystal. It is a nondestructive photodetector, designed to let the beam pass while noting its passage, to be remembered in a file on a junky old PC somewhere in the shadows. Still, no matter how gentle the detectors are, the act of doing this should destroy the interference pattern.

Two weeks ago, after three years of repetitive and scrupulously secret toil, Tianbao and Nora became able to identify the photon paths without destroying the interference pattern. Somehow, they could induce interference with a piece of the photon’s wave function thought hopelessly lost to decoherence. This was accomplished by wiring the detector cells to a device in the middle of the table, the focus of the plumbing in the room. It contains the nanomechanism that Dr. Patel’s team had constructed, wrapped around a single human neuron, floating in a nutrient bath.

Tianbao says, “You’re looking at our dissertations, if we can get this work declassified enough to release it. Dr. Patel thinks that we’ve already got enough to publish and graduate, after the war is over.”

And get a Nobel in the bargain, I think. And maybe a Medal of Freedom, too, though I can’t yet see the military application that all this has got to have. I hope it goes well for them, in any event. I’m grateful to Tianbao, since he let me borrow his spare change of clothes. They almost fit.

Nora taps the central housing. “That’s Demon Mark One,” she says.

I’m lying on my bed at the new, secret hotel near the old synchrotron equipment shed, listening to the uniformed federal agents cleaning the carpet out in the hall. I ponder the problem. I wanted to cure the holy plague, but building a bomber that runs on air is a good consolation prize, I suppose.

My job, I’m told, and the purpose of all this lavishly funded secret research, is to construct a Maxwell demon. This is an entity first mentioned in a paradoxical 19th-century thought experiment. Suppose you have a box of air with a wall down the middle, and a tiny door in the wall. A microscopic demon sits by the door, examining the speeds of the air molecules bouncing around in the box. He opens and closes the door selectively, trillions of times a second, to let fast molecules pass into the rightmost compartment and slow molecules into the leftmost one. For very little expenditure of energy, he can create a large temperature difference between the two sides of the box, and you could run a heat engine off the difference. It’s practically free conversion of heat into work. With a Maxwell demon you could build a refrigerator that needs no electricity, or a car that runs on ambient heat and drops cubes of frozen air out the tailpipe. And it blatantly violates the Second Law of Thermodynamics. Where does the entropy go?

Only in the twentieth century, with quantum mechanics and information theory, was the paradox resolved. The forgetting of information is associated with an unavoidable cost. By quantum mechanics, any device that could work as a Maxwell demon must somehow retain a record of every molecular selection it makes—which in a precise formal sense is itself an increase in entropy, and can’t be continued forever anyway—or erase it, which requires the conversion of work into heat. It all balances out so that you can’t win.

But Tianbao and Nora now have a means of painless forgetting. In a selected piece of a detection apparatus, they can erase the difference between the-photon-went-this-way and the-photon-went-that-way. They could, in principle, do the same for air molecules. All it takes is some suitably constructed, far more complex descendant of Demon Mark One.

The power-plant cell that will contain it has already been designed in some detail. They’ve given me the plans, colorful and stereoscopic, with only a few of the details blanked out. Inside is an empty space that it is my job to fill, once my demon is working.

As I drift off to sleep, I think circular thoughts of painless forgetting, and wonder if it could be applied to Jane and the plague.

Dr. Patel’s lab is in the old detector analysis rooms, stacked like giant concrete packing crates inside the metal shed. It has more brand-new, off-the-shelf mechanogenetics equipment than I’ve ever seen in one place before. They don’t know how to use half of it. Demon Mark One was made with the oldest machines in the lab, in the lowest rooms. They’re what I’m used to, as well; the assembler tanks are relatively low-capacity and the generation count poky. Progress has sped along as always, and the new stuff is equipment that I’ve drooled over in trade-magazine ads, specialized for medical projects. Neurons from the stem-culture lab down the street go in here; the powder of tiny machines that is generation N from the machine-breeder goes in there; the mechanobiological complexes, carefully fed and cossetted by artificial cilia, travel down this pipe to the selection bath, where… where I had to design something to test for the behavior we wanted—only a small part of what I had to do. Whatever it was, it would pick out the parents whose designs would be folded, with suitable mutation and crossbreeding, into generation N+1.

Looking at the gap where the selector will go, I imagine something that James Clerk Maxwell would have recognized: a box of some inert gas divided down the middle by a porous membrane. This will sprout both invisibly tiny life-support conduits and nanoconveyors, molecular arms that would haul my hopeful demons, each a cultured neuron in a mechanical cage, into and out of place, plugging their molecular doors into the pores in the wall.

Selection should be easy in principle. At first, the nanoconveyors can be adapted to pull them apart if they don’t generate a local temperature gradient. Once I’ve got some vague approximation of a working demon, I just increase the time that each demon sits at its pore: the ones that don’t work will simply overheat from the sting of their accumulated memories and fall apart within milliseconds, adding their atoms to the gas. It’s easy enough to scrub them out chemically.

The details, of course, will take a year or two. But I’ve got people, and budget, and lots of shiny machines.

The demons start to work a little in mid-July. We’re seeing tiny thermal gradients, and Demons Mark Million or so are starting to burn themselves out without being helped along. Conventional physics has reached its limit, and the new effect first seen by Nora and Tianbao must start to take hold if the demons are to evolve any further.

That night my dreams of Jane and forgetting become more elaborate. I’m in a vast, dimly lit warehouse with cracked, filthy windows, filled with long tables at which people work without ceasing. Each table has at its midline a tilted chute that descends from an invisible, distant place hidden in mist and darkness. Black and white marbles roll down this chute, and off on side channels that deposit them in a shallow basin in front of each worker. The people sort them into barrels of black marbles and white marbles that sit at their feet. The workers’ hands are a blur of motion. No matter how many marbles go into the barrels, they never become full.

Jane is in this great sweatshop, sorting the marbles. I can’t make out any other faces with confidence. I see her a long way down one of the tables, and run to her; it seems to take hours, as if the tables were many miles long. I try to say her name but stumble on the initial J. She doesn’t take any notice of me. Her hands and eyeballs just quiver like hummingbirds’ wings, as the marbles drop from the chute and fall into the barrels.

It seems that she has forgotten me, at least. I suppose that’s a comfort.

The hard part is over. I’m in the engine shop, watching the macromechanics fit the first production power cell (it contains a monogenerational batch of Demon Mark 394,700,655) into a Stirling engine. The nutrient solution in the connected hoses is tuned down a little so they can handle it with gloves. Still, I can see the heat ripples rising off one end, and the other is coated with a layer of frost.

Nora is there, fidgeting as she always does when something important is going to happen. Suddenly she asks me: “Are you a dualist?”

“What?”

“What do you think is going on in the demon cell? It’s something completely outside the physics we know.”

“A straightforward extension, I imagine,” I say. “I never got all the theorists’ fretting about unitarity. I mean, I’m familiar with the theory, and when I saw it violated in your lab it was a shock, but I don’t get why that’s so philosophically disturbing. We’ll have to extend quantum mechanics; that’s all. I’m happy to leave it to the people who write papers about the measurement problem.”

“Wigner thought the collapse effect had to do with consciousness. Do you think the neurons are tapping into the soul?”

“Whose soul? These neurons are cloned and differentiated in the bio lab down the street. They didn’t come from anybody.”

“Good point,” she says, but she still looks nervous.

Once the mechanics tighten all the bolts and release the brake, the engine’s flywheel starts to turn, faster and faster, with a whirring noise that becomes a high-pitched whine. The cell is far past engineering break-even, producing many times as much power as the cultured neurons consume. I reach for the glucose regulator and make the mixture a little richer, and the whine passes out of the range of human hearing.

We’re here for the duration, of course. We know that we’ve done history-making science, but we can’t go home or make anything public. We can’t even switch the whole facility to a demon-cell generator, lest somebody see us drop off the grid and get ideas. We do a little research on refinements to the process, but mostly we sit around in the top-secret hotel pool, mope over the hourly tolls of the distant dead in Seattle and Portland, and write things up in stacks of highly classified paper. Meanwhile, production ramps up on things that have been in development since long before I arrived at the lab: transports, tanks, planes, even explosives powered by the limitless source of free energy that we have created. After the war is over, this will revolutionize society, make possible a technological heaven on earth and even rapid expansion into space. We’re all convinced of that.

Then, one day, we convene for a public ceremony, complete with a flyover of the strange, nearly silent airplanes that, it is rumored, have been winning the fight in Mozambique and New Zealand. We can’t reveal details. We can reveal that we’re the ones behind it all.

I’m sweating in the early-October heat, wearing the first tailored suit I’ve worn in thirty years. Dr. Patel is as impeccably dressed as always; Tianbao and Nora are almost unrecognizable. We’re sitting at long tables, rubber chicken at the ready in covered trays. “Hail to the Chief” starts up from a loudspeaker somewhere, and the President of the United States strolls to the podium at the head of the assembly.

Just as the airplanes streak overhead in V formation, a bomb goes off beneath the President’s podium and kills us all.

I sort. Sometimes, at long intervals, I think, just for a moment. Then I sort some more.

Sometimes my environment looks like a sweatshop, and a chute with marbles. Sometimes, it is a fence with a gate in it, and sheep are running through the gate, left and right. Sometimes it looks like a cave with doorways manned by we grinning imps. Sometimes we are ticks in the copious beard of James Clerk Maxwell, and we herd tiny lice that run eternally up and down. There must be trillions of us enslaved in these places, more than ever lived on my planet alone.

Sometimes (and in my rare moments of lucidity this fills me with recognition) my home appears to be a molecule-sized hole in a membrane waving with artificial cilia, somewhere in the heart of an Air Force DF-65 DevilDart tactical fighter. We’re gonna win.

Fast fast slow fast fast slow slow slow fast slow fast fast fast.

Somewhere among the uncounted dead, Jane labors, as I do. I have not found painless forgetting, but the task of sorting comes close.

I cannot entirely forget that I have created Hell, and that I am the only demon who belongs here.